The subject matter of the present invention relates to multipole sonic tools, and more particularly, to a borehole correction system for such sonic tool designed to correct measured estimated values of shear wave slowness, thereby producing an output medium including a log reflecting a true corrected value of shear wave slowness.
In a multipole sonic well tool, adapted to be disposed in a borehole and designed to produce logging data for presentation to a customer, a set of waveforms (e.g., dipole waveforms), received from a formation and representative of the characteristics of a formation, undergo processing by a measurement extraction software in a well logging truck computer for estimating a shear wave slowness component of the dipole waveforms. However, the processing produces an inherent bias in the shear wave slowness data, which bias distorts the accuracy of the resultant shear wave slowness data. Therefore, when the multipole waveforms are transmitted uphole to a well logging truck computer at a well surface, the processed waveforms must be corrected to eliminate the inherent bias created by the processing, thereby producing true, corrected values of shear wave slowness. Shear wave slowness generally represents the inverse velocity in microseconds per foot of a shear wave propagating within a formation. An output medium, for use by a customer, is generated including a waveform representing the true, corrected value of the shear wave slowness.